main.dart

import 'dart:math';

void main() {
  var input = getSeriesOfNumbersWithAnOddNumberOfTimesEncounteredElement(10);
  
  
  
}

Iterable<int> getSeriesOfNumbersWithAnOddNumberOfTimesEncounteredElement(int length) {
  List<int> original = [];
  List<int> result = [];
  for (int i = 0; i < length; i++) {
    var n = Random().nextInt(255);
    if (!original.contains(n)) {
      original.add(n);
    } else {
      i--;
    }
  }

  var odd = original.removeLast();
  print("odd: $odd");

  result.addAll(List.filled(getRandomOdd(10), odd));

  for (var n in original) {
    result.addAll(List.filled(getRandomEven(10), n));
  }

  result.shuffle();
  return result;
}

int getRandomOdd(int max) {
    var n = Random().nextInt(max);
    return n%2==1? n:n+1;
}

int getRandomEven(int max) {
    var n = Random().nextInt(max);
    return n%2==0? n:n+1;
}